Compact Muon Solenoid
LHC, CERN
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| CMS-PAS-BPH-22-003 | ||
| First observation of the rare 4 $ \mu $ decay of the $ \eta $ meson | ||
| CMS Collaboration | ||
| 25 February 2023 | ||
| Abstract: The first observation of the double-Dalitz decay $ \eta \rightarrow \mu^+\mu^-\mu^+\mu^- $ is reported with 2017 and 2018 data by the CMS experiment at the CERN LHC. A signal having a statistical significance well in excess of 5 standard deviations was identified using high-rate muon trigger data collected at a proton-proton collision center of mass energy of 13 TeV corresponding to an integrated luminosity of 101 fb$ ^{-1} $. Using the $ \eta \rightarrow \mu^+\mu^- $ decay as normalization, the branching fraction $ \mathcal{B}(\eta \rightarrow \mu^+\mu^-\mu^+\mu^-) = $(5.0 $ \pm $ 0.8 (stat) $\pm$ 0.7 (syst) $\pm$ 0.7 ($\mathcal{B}$)) $\times$ 10$^{-9} $ is measured, in agreement with theoretical estimates. | ||
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Links:
CDS record (PDF) ;
Physics Briefing ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PRL 131 (2023) 091903. The superseded preliminary plots can be found here. |
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Compact Muon Solenoid LHC, CERN |
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